Transformer core assembly fixture



June 20, 1967 w. OLSEN 3,325,886

TRANSFORMER CORE ASSEMBLY FIXTURE Original Filed Oct. 24, 1963 4Sheets-Shet 1 if" INVENTOR. v

WILLY OLSEN June 20, 1967 w, OLSEN 3,325,886

TRANSFORMER CORE ASSEMBLY FIXTURE Original Filed Oct. 24, 1963 4Sheets-Sheet 2 INVENTOR.

NlLLY OLSEN June 20, 1967 w. OLSEN 3,325,886

TRANSFORMER CORE ASSEMBLY FIXTURE Original Filed Oct. 24, 1963 4Sheets-Sheet 3 m N NE w s NI 0 Y L w w June 20, 1967 w. OLSENTRANSFORMER CORE ASSEMBLY FIXTURE Original Filed Oct. 24, 1963 4Sheets-Sheet 4 INVEN'I 'OR. W l LLY OLSEN United States Patent 5 Claims.c1. 29-403 This application is a division of application Ser. No.318,726, filed Oct. 24, 1963.

This invention relates generally to apparatus for assembling wound typetransformer cores of the type shown and described in detail in thec0-pending United States patent application of Willy Olsen and Howard D.Tindall, Ser. No. 151,655, filed Nov. 13, 1961, and entitled,Transformer Core Construction and Method of Producing Same, now PatentNo. 3,223,955, granted Dec. 28, 1965.

Wound transformer cores of this type have superior magneticcharacteristics resulting in lower core losses and higher transformerefficiencies. The superiority of wound transformer cores as compared tocores made of solid sections or punched laminations is well known toworkers in the art and need not be detailed herien. Moreover, it is alsoknown that a wound transformer core made from a single continuouslywound strip of core material will normally exhibit better magneticpropeties than a transformer core fabricated from a plurality of stripswhich have ends butted or lapped to form a composite core. Nevertheless,as a practical matter, manufacturing economics dictate that wound coresshould be made from a plurality of strips of core material rather thanfrom a single continuous strip even though the joints inherent in such aconstruction tend to degrade the magnetic efficiency of the corestructure. Therefore, considerable effort has been concentrated uponways of minimizing the deleterious effects of the joints whilemaintaining the manufacturing benefits which flow from the jointed typeof core construction.

In nearly all instances it is desirable to form a transformer core sothat it is of rectangular or square shape having a correspondingrectangular or square central opening or window to accommodate thetransformer coil structure in order that the over all transformer may bemade as compact as possible, the composite transformer usually includingat least two cores each of which is disposed about one leg of the coilstructure so that one leg of each core is disposed within the coilwindow in such manner as to cause the coil window to be substantiallycompletely filled. This type of structure creates problems which regardto the installation of the preformed cores through the coil window sincethere is very little unoccupied coil window space in the finishedassembly and the corners of the core structure must be passed throughthe window in order to close the core.

The preformed core corners are necessarily deformed by straightening inorder to be passed through the window, particularly with regard to theouter laminations of the cores, with the consequent introduction ofmechanical stresses and strains into the laminations of the cores. Theintroduced stresses alter the magnetic properties of the core in anadverse manner and are, of course, undesirable. This condition isaggravated in most wound core constructions by the fact that the corelaminations have a high space factor at the corners and are preventedfrom readily shifting relative to one another as they are stressed whilebeing passed through the coil window. This increases the strainsintroduced at the corners and further degrades the core performance.

Attempts have been made in the past to reduce the severity of thisproblem by the use of various forming methods directed toward reducingthe space factor at the corners, as for example by the use of insertshims in the corner regions as the core is being wound. Unfortunately,these known methods are either uneconomic or also tend to reduce thespace factor in the straight sided legs and yoke regions of the corewhere a high space factor is desirable. The superior transformer coreconstruction fully described and illustrated in the aforesaid copendingUnited States Patent application, and which is also shown in thedrawings appended hereto is economically producible by utilization ofthe apparatus and method according to the present invention to behereinafter described.

A primary object of this invention is to provide novel apparatus for anda method of making a wound trans former core of rectangular or squareform characterized by a high space factor throughout the straight sidedregions of the core together with a space factor at the corners of thecore sufficiently low to allow for relatively free interlaminar movementduring assembly of the core to its coil structure to thereby prevent thecreation of mechanical streses and strains in the core material andpreserve the magnetic properties of an unstressed core.

Another object of this invention is to provide a novel apparatus for andmethtod of making a wound transformer core structure which is built upfrom a plurality of internested core sections wherein the outermost coresection functions as a retainer for the additional core sections nestedsuccessively therewithin.

A further object of this invention is to provide novel apparatus forfabrication of the wound core structure including an open ended boxstructure within which the core sections are internested prior toforming into the ultimately desired shape to transport the unformedinternested core sections from an assembly point to a forming apparatus,whereby the forming apparatus may be operated continuously.

Yet another object of this invention is to provide a novel apparatus formaking wound transformer cores which includes a multiple part annealingbox structure which is assembled about the wound core structure duringthe course of forming the same from the internested unformed coresections.

A further object of this invention is to provide novel apparatus forremoving the annealed formed core structure from the aforesaid annealingbox without subjecting the annealed core to mechanical strains andstresses which would impair the magnetic properties of the core.

The foregoing and other objects of the invention will become clear froma reading of the following specification in conjunction with anexamination of the appended drawings, wherein:

FIGURE 1 illustrates a perspective view of the open ended assembly boxwithin which the several unformed core sections are to be internested;

FIGURE 2 illustrates the assembly box of FIGURE 1 with a pair of sideplates disposed therewithin effective to cover the side openings throughthe assembly box;

FIGURE 3 is a perspective view illustrating the disposition of the coresections into the assembly box in order beginning with the outermostsection and ending with the innermost section;

FIGURE 4 illustrates a top plan view of the assembly box with all of thecore sections internested and disposed therewithin;

FIGURES 5 and 6 illustrate the application of pressure to the sideplates of the assembly box to move the same inward and permit removal ofthe assembly box upward and away from the core assembly;

FIGURES 7 and 8 show successive steps in forming the core to the desiredrectangular shape;

FIGURES 9 through 15 illustrate the steps of constructing the annealingbox about the formed core; FIGURE 10 3 being a partial vertical sectionas would be seen when viewed along the line -10 of FIGURE 9;

FIGURES 16 through 20 illustrate the apparatus for and steps carried outin removing the annealing box from the annealed formed core, FIGURES l6and 17 being side and top views respectively of the apparatus as wouldbe seen when viewed along the lines 16-16 and 17--17 of FIGURES 17 and16; and

FIGURE 21 is a perspective of the finished core formed by the apparatusand method of the present invention.

In the several figures, like elements are denoted by like referencecharacters.

Referring now to the figures, consider first FIGURES 1 to 4 in whichthere is seen the core assembly box and the unformed core structure 31made up of a plurality of concentrically internested annular coresections 32 through 35. Each of the core sections 32 through is made upof a plurality of concentrically internested end abutting strips withthe end abut-ments of the strips being successively offset from oneanother in staircase fashion. The end abutment regions of each of theouter core sections 32, 33 and 34 are observed to be themselves disposedin offset fashion along one side of the core assembly while the endabutments of the innermost core section 35 are observed to be disposeddiametrically across the core. This arrangement of the end abutments ofthe several core sections which together make up the composite core isfor the purpose of subsequently providing optimum ease of assembly ofthe finished structure through the windows of the coil structure withwhich the cores are to be used in forming a finished transformer, all asset forth in detail in the aforementioned copending patent application.

The core assembly box 30 is of rectangular parallelepiped form with thetop and bottom surfaces removed having a pair of opposite end walls 36and a pair of opposite side walls 37, the side walls 37 beingrectangularly substantially centrally aperturcd upwardly from the bottomedge of the box and stopping short of the top edge so that the. sidewalls 37 appear generally to be of inverted U shape. Secured 'to theinside face of each of the sidewalls 37 at opposite side edges of therectangular apertures through the side walls are vertically extendingguides 38 between which are removably disposed side plates 39 whichcover the apertures through the side walls 37 As will be subsequentlyseen, these side plates 39 also form part of the annealing box andfunction as pressure applying platens which are acted upon by the ramsof the forming device.

The core 31 is now built up in the core assembly box 30 between the sideplates 39 by first placing the outermost core section 32 downward withinthe box in a manner best seen in FIGURE 3. The outer lamination of thecore section 32 has its abutting ends secured together by means of apiece of tape to prevent the natural resilience of the core stripmaterial from causing this core section to spring open, the outer coresection being hand forced into a generally ovoid shape, as seen inFIGURE 4, so that the resilience of the section causes it to expand intofirm engagement with the side plates 39 to thereby positionallystabilize the core section within the assembly box. The inner coresections are now successively internested within the outer core section32 to form the composite unformed core 31 held securely within the coreassembly box 30 and ready for forming.

The assembly of an unformed core into a core assembly box, as justdescribed, may be carried out at any convenient location and notnecessarily at the forming apparatus. Consequently a number of suchunformed cores may be assembled at a convenient location and may be thentransported to the forming apparatus so that the cores may be thensuccessively formed one immediately after the other with no loss of timeat the forming apparatus as would be the case if it were necessary toassemble each of the unformed core structures at the forming apparatus.In this way, the production efl iciencies are realized.

Refer now to FIGURES 5 through 8 in order, the core assembly box 33containing an unformed core 31 is placed upon the table of the formingapparatus with the open bottom ends of the apertures through the sidewalls 37 being disposed downward and in alignment with a pair of spacedapart colinearly disposed rams 4d at least one of which is reciprocablerelatively to the other. As best seen in FIGURE 5, one of the rams 40 isdriven toward the other so as to clamp the side plates 39 between therams 4d, the rams engaging the outer surfaces of the side plates throughthe openings in the assembly box side walls 37. The ram motion iscontinued until the side plates 39 are moved toward one anothersufficiently to disengage the same from the assembly box 30, the cor-e31 of course becoming more elongated in the process. The core box 30 isthus disengaged from the side plates 39 and may be lifted verticallyupward and completely removed, in the manner seen in FIGURE 6.

With the core 31 in its elongated form as seen in FIG- URES 5 and 6, amandrel 41 of generally rectangular shape is placed within the elongatedcentral opening of the core and the compressive action of the rams 40is' resumed until the inside lamination of the innermost core section ispressed firmly against opposite sides of the mandrel 41 in the mannerillustrated in FIGURE 7, it being observed that the joints of the coresections are tightly clamped between the central mandrel 41 and the sideplates 39. A pair of opposite end plates 42 are now moved intoengagement with opposite ends of the core 31 by means of a pair of endrams 43, the ram pressure being continuously exerted until the ends ofthe core 31 are squared off in the manner illustrated in FIGURE 8.

As also best seen in FIGURE 8, it is observed that the central openingof the core has also become rectangular and that gaps 44 are observed tointervene the adjacent core sections at the corners of the core.Additionally there also exist slight gaps between the individuallaminations of each core section in these same corner regions althoughthese cannot be clearly shown on the drawing. This looseness in thecorners reduces the space factor in these regions of the core so thatthe core sections may be much more readily flexed when installing thesame through the window of the preformed coil structure to therebyeliminate the high merchanical stresses which adversely affect the coremagnetic characteristics and which are developed in core structureswhich have high space factors in the corner regions thereof.

As best seen in FIGURES 9, l0 and 11, with the core formed as shown inFIGURE 8 and with the side plates 39 and end plates 42 in position asshown, an annealing box frame 45 of rectangular shape and provided withdepending side flanges 46 is fitted downward upon the upper surface ofthe core 31 so that the side flanges 46 close fittingly enclose theupper outer marginal edges of the sides plates 39 and end plates 42. Thelower edges of the side flanges 46 are cut upwardly inward as at 47 forreasons which will subsequently appear, and the central part of theframe 45 is cut out as at 48 so that heat from the annealing oven maycirculate freely through the inside region of the formed core.

The rams 40 and 43 are now retracted and the core 31 with the enclosingside and end plates and annealing box frame 45 is turned upside down asa unit as shown in FIGURE 12. The rams 40 and 43 are now again movedinwardly into engagement with the side plates 39 and end plates 42 tocompress the same so that a second annealing box frame 45 may be moveddownward into seating engagement with the core 31 to enclose also thefree upper marginal edges of the side plates 39 and end plates 42 asshown in FIGURES 13 and 14. The rams 40 and 43 are again retracted, asin FIGURE 14, and the composite assembly of the formed core within itsannealing box may now be removed from the forming apparatus masses andwill appear as shown in FIGURE 15. The boxed formed core may now beannealed, subsequently cooled, and then the core may be removed from theannealing box in the manner to be now described.

Turning now to FIGURES 16 through 20, consider first FIGURES 16 and 17which illustrate a rectangular table frame 49 supported by legs 50 andsupporting a magnetically susceptible top plate 51, as for example madeof steel plate. Spaced downwardly from the top 51 and extendingtransversely therebeneath and secured at opposite ends to the tablesupport structure are a pair of spaced apart horizontal supports 52which carry thereupon a magnet structure including an energizable field53 and poles 54, the poles 54 being in surface contact with theunderside of top plate 51. Fixedly secured to and extending upward fromthe frame 49 is a support frame having a pair of vertical members 55which carry a transversely extending horizontal top member 56, members55 and 56 being illustrated as of channel shape in cross section.

Suspended vertically from the horizontal top support 56 as by means of asuspension bolt 57 is a cylinder 58 within which is disposed forvertical reciprocation a piston head which is connected to the pistonrod 59 observed in FIGURE 16 to extend below the cylinder 58. The pistonmay be moved upward within the cylinder 38 by injection of hydraulicpressure through the port 60 and venting through the port 61, while thepiston may be lowered by the reverse procedure. The piston rod 59 willof course rise or lower in accordance with the motion of the piston headwithin the cylinder 58 and will carry with it the triangular frame 62coupled to the lower end of the piston rod 59 as by means of the shackle6 3. The triangular frame 62 includes a horizontally extending bar 64whose opposite ends terminate in vertically oriented cylindrical sleeves65 disposed within the channel shaped vertical supports 55 and throughwhich vertically extend the guide rods 66 which latter are fixedlysecured to the vertical supports 55 as by means of the anchor blocks 67seen in FIGURE 16. Slidably disposed upon the horizontal bar 64 of thetriangular frame 62 are a pair of hooks 68 whose hook like projectionsare pointed toward one another and inclined upward as most clearly seenin the showing of FIGURE 20.

The annealed formed core 31 enclosed within the annealing box in themanner shown in FIGURE 15 is placed upon the top plate 51 above themagnet structure so that one of the annealing box frames 45 is disposedfiatwise upon the top plate in generally overlying relation to themagnet structure, the annealing box being so positioned that the hooks68 may be moved inward toward it along the horizontal bar 64 of thetriangular frame 62 to permit the upwardly turned hook ends to underliethe inwardly upwardly cut lower edges 47 of the side flanges 46 of theupper annealing box frame 45.

The magnet structure is now energized to strongly magnetically hold theannealing box and core contained therewithin downward upon the top plate51. Next, the slidable hooks 68 are moved inward to underlie theopposite ends of the frame side flanges as shown by the dotted lineshowing in FIGURE 16. The piston within the cylinder 58 is now subjectedto upward lifting force by hydraulic or pneumatic pressure appliedthrough the cylinder port 60, thus causing the piston rod 59 to rise andcarry with it the tri-angular frame 62 and slidable hooks 68. The hooks68 anchor under the annealing box frame side flanges 46, as shown in thedetail of FIGURE 20, and continued upward movement of the frame 62results in the upward removal of the annealing box upper cover 45 asillustrated in FIGURE 18. The magnet structure is now deenergized andremoved frame 45 is lifted from the hooks 68 and set aside, after whichthe hooks 68 are slid outward away from one another and the frame 62 isagain lowered by releasing the pressure on the piston within thecylinder 58.

With the magnet deenergized the partially housed core structure may nowbe turned top for bottom so that what was formerly the bottom frame ofthe annealing box now becomes the top frame. The magnet structure is nowagain reenergized and the hooks 68 are slid inward to underlie the sideflanges 46 of the remaining annealing box frame 45, after whichactuation of the piston removes this remaining frame 45. Deenergizationof the magnet now releases the side plates 39 and end plates 42 of theannealing box structure from the finished core 31, this beingillustrated in the showing of FIGURE 19. The mandrel 41 may now belifted out of the core Window to leave the completed annealed formedcore 31 which appears as shown in FIGURE 21.

Having now described my invention in connection with particularlyillustrated embodiments thereof it will be appreciated thatmodifications and variations of the same may now occur from time to timeto those persons normally skilled in the art without departing from theessential scope or spirit of my invention, and accordingly it isintended to claim the same broadly as well as specifically as indicatedby the appended claims.

What is claimed as new and useful is:

1. An assembly device for holding the internested plural turns of acentrally windowed unformed wound transformer core prefatory to forming,comprising in combination, a pair of spaced apart parallel vertical wallmembers each of a which has an area cut thereout of extending upwardfrom the bottom edge thereof, a rigid plate member removably disposedagainst the inside face of each said wall member in covering relation tothe cut out area of said wall member, and means fixedly conmeeting saidwall members together at a desired spacing of such length that theunformed core must be laterally compressed from opposite sides to anovoid shape in order to fit between the said plate members, the latterbeing movable inwardly of the wall members with which they arerespectively associated by pressure applied thereto externally of saidwall members through said cut-out areas for compression of the core heldin said device.

2. An assembly device as defined in claim 1 wherein said plate membersare each of substantially the same height as the core to be disposedtherebetween and of a length somewhat less than that of the core whenthe latter has been formed.

3. An assembly device for holding the internested plu ral turns of acentrally windowed unformed wound transformer core prefatory to forming,comprising in combination, a pair of rigid parallel vertical platemembers spaced apart by a distance of such length that the unformed coremust be laterally compressed to an ovoid shape in order to fittherebetween, and retainer means detachably engaged with said platemembers effective to prevent the latter from moving away from oneanother when a core is disposed therebetween, said retainer means beingdetachable from said plate member when the latter are moved toward oneanother to increase the compression on the core.

4. A device for holding the internested plural turns of an unformedwound transformer core having a central window, comprising, a hollow boxof rectangular parallelpiped shape having an open top and bottom formedby a pair of parallel spaced apart sidewalls and a pair of parallelspaced apart end walls, the said pairs of walls being mutuallyperpendicular and rigidly connected together at their ends, the spacingbetween said sidewalls being somewhat less than the diameter of thelargest turn of the unformed wound core so that the unformed core mustbe laterally compressed from opposite sides into an ovoid shape in orderto fit between the said sidewalls, the spacing between said end wallsbeing greater than the maximum lateral extent of the core when disposedin the box so that the end walls are spaced outward away from the coreends, both of said side walls having a central area cut away upward fromthe bottom edge thereof toward the top edge, and a rigid metal sideplate freely disposed against the inside of each side wall, said sideplates being substantially the same height as the core to be disposed inthe box and of a length somewhat less than that of the core when thelatter has been formed, said box and side plates and unformed core beingheld together as a unit by the outward directed force exerted by thecompressed core on the side plates and hence on the box sidewalls.

5. A device as defined in claim 4 including vertically extending guideelements fixed t0 the inside face of each side wall at opposite sides ofits cut away central area,

each of said side plates being closely fitted between a pair of saidguide elements.

References Cited UNITED STATES PATENTS JOHN F. CAMPBELL, PrimaryExaminer.

THOMAS H. EAGER, Examiner.

1. AN ASSEMBLY DEVICE FOR HOLDING THE INTERNESTED PLURAL TURNS OF ACENTRALLY WINDOWED UNFORMED WOUND TRANSFORMER CORE PREFATORY TO FORMING,COMPRISING IN COMBINATION, A PAIR OF SPACED APART PARALLEL VERTICAL WALLMEMBERS EACH OF A WHICH HAS AN AREA CUT THEREOUT OF EXTENDING UPWARDFROM THE BOTTOM EDGE THEREOF, A RIGID PLATE MEMBER REMOVABLY DISPOSEDAGAINST THE INSIDE FACE OF EACH SAID WALL MEMBER IN COVERING RELATION TOTHE CUT OUT AREA OF SAID WALL MEMBER, AND MEANS FIXEDLY CONNECTING SAIDWALL MEMBERS TOGETHER AT A DESIRED SPACING OF SUCH LENGTH THAT THEUNFORMED CORE MUST BE LATERALLY COMPRESSED FROM OPPOSITE SIDES TO ANOVOID SHAPE IN ORDER TO FIT BETWEEN THE SAID PLATE MEMBERS, THE LATTERBEING MOVABLE INWARDLY OF THE WALL MEMBERS WITH WHICH THEY ARERESPECTIVELY ASSOCIATED BY PRESSURE APPLIED THERETO EXTERNALLY OF SAIDWALL MEMBERS THROUGH SAID CUT-OUT AREAS FOR COMPRESSION OF THE CORE HELDIN SAID DEVICE.